(Phys.org) —Splitting water into its components, two parts hydrogen and one part oxygen, is an important first step in achieving carbon-neutral fuels to power our transportation infrastructure – including automobiles ...

Chemical engineers at Rice University have found a new catalyst that can rapidly break down nitrites, a common and harmful contaminant in drinking water that often results from overuse of agricultural fertilizers.

(Phys.org) —A substance made from gelatin could be used to replace platinum in fuel cells, according to research published by University of Birmingham scientists in the Royal Society of Chemistry Journal of Materials Chemistry ...

Researchers report that they have created a man-made catalyst that is an "enzyme mimic." Unlike most enzymes, which act on a single target, the new catalyst can alter the chemical profiles of numerous types of small molecules. ...

The addition of functional groups to certain unsaturated hydrocarbons, known as alkenes, is a crucial stage in the synthesis of various compounds, including many plastics. For these functionalization reactions to occur a ...

Chemists from Nijmegen, The Netherlands, have developed a catalyst that binds to DNA, slides over it and splits the molecule in particular places. The researchers were able to do this by synthetically modifying a natural ...

Researchers from Ulsan National Institute of Science and Technology (UNIST), Korea Institute of Energy Research (KIER), and Brookhaven National Laboratory, have discovered a new family of non-precious metal catalysts. These ...

(Phys.org) —In the growing area of flexible, transparent electronic devices, silicon has not played much of a role. Instead, materials such as indium tin oxide, carbon nanotubes, and others are often used to make bendable ...

MIT researchers have found a new family of materials that provides the best-ever performance in a reaction called oxygen evolution, a key requirement for energy storage and delivery systems such as advanced fuel cells and ...

Catalysis

Catalysis is the process in which the rate of a chemical reaction is either increased or decreased by means of a chemical substance known as a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. The catalyst may participate in multiple chemical transformations. Catalysts that speed the reaction are called positive catalysts. Catalysts that slow down the reaction are called negative catalysts or inhibitors. Substances that increase the activity of catalysts are called promoters and substances that deactivate catalysts are called catalytic poisons. For instance, in the reduction of ethyne to ethene, the catalyst is palladium (Pd) partly "poisoned" with lead(II) acetate (Pb(CH3COO)2). Without the deactivation of the catalyst, the ethene produced will be further reduced to ethane.

The general feature of catalysis is that the catalytic reaction has a lower rate-limiting free energy change to the transition state than the corresponding uncatalyzed reaction, resulting in a larger reaction rate at the same temperature. However, the mechanistic origin of catalysis is complex. Catalysts may affect the reaction environment favorably, e.g. acid catalysts for reactions of carbonyl compounds, form specific intermediates that are not produced naturally, such as osmate esters in osmium tetroxide-catalyzed dihydroxylation of alkenes, or cause lysis of reagents to reactive forms, such as atomic hydrogen in catalytic hydrogenation.

Kinetically, catalytic reactions behave like typical chemical reactions, i.e. the reaction rate depends on the frequency of contact of the reactants in the rate-determining step. Usually, the catalyst participates in this slow step, and rates are limited by amount of catalyst. In heterogeneous catalysis, the diffusion of reagents to the surface and diffusion of products from the surface can be rate determining. Analogous events associated with substrate binding and product dissociation apply to homogeneous catalysts.

Although catalysts are not consumed by the reaction itself, they may be inhibited, deactivated or destroyed by secondary processes. In heterogeneous catalysis, typical secondary processes include coking where the catalyst becomes covered by polymeric side products. Additionally, heterogeneous catalysts can dissolve into the solution in a solid-liquid system or evaporate in a solid-gas system.